Heat transfer system

ABSTRACT

The memory module comprises a circuit board with a first and a second side, wherein memory chips are arranged at least on the first side. A longitudinally extending module heat conductor is arranged on the first side. The module heat conductor comprises a contact surface configured to contact a heat transfer system.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims foreign priority benefits under 35 U.S.C. §119to co-pending German patent application number DE 10 2007 045 733.4,filed Sep. 25, 2007. This related patent application is hereinincorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to transfer of heat in electronic systems.In particular the invention relates to a memory module, a circuit board,a computer system and a heat transfer system.

2. Description of the Related Art

For computer systems, for example server, desktops or laptops an ongoingtrend towards compact design with expanded memory capacity isrecognized. This and the always increasing clock-rates of memory lead toincreased waste heat of computer systems. Already the maximum amount ofmemory of a computer system is limited by thermal conditions in someapplications. Therefore a need for concepts for cooling exists.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of embodiments of the present invention and areincorporated in and constitute a part of this specification. Thedrawings illustrate the embodiments of the present invention andtogether with the description serve to explain the principles in anon-limiting manner. Other embodiments of the present invention and manyof the intended advantages will be readily appreciated as they becomebetter understood by reference to the following detailed description.The elements of the drawings are not necessarily to scale relative toeach other. Like reference numerals designate corresponding similarparts.

FIG. 1 illustrates a schematic top view of a computer system and of aheat transfer system, according to one embodiment of the invention;

FIG. 2 illustrates a schematic side view of a computer system and of aheat transfer system, according to one embodiment of the invention;

FIGS. 3A, 3B, 3C show views of a memory module and heat transfer system,according to one embodiment of the invention;

FIGS. 4A, 4B show detailed views of the heat transfer system, accordingto one embodiment of the invention;

FIGS. 5A, 5B, 5C show a use of a memory module and a heat transfersystem, according to one embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

In the following detailed description reference is made to theaccompanying drawings, which form a part hereof, and in which is shownby way of illustration specific embodiments in which the invention maybe practiced. In this regard, directional terminology, such as “top”,“bottom”, “front”, “back”, “leading”, “trailing” etc., is used withreference to the orientation of the figures being described. Becausecomponents of embodiments of the present invention can be positioned ina number of different orientations, the directional terminology is usedfor purposes of illustration and is in no way limiting. It is to beunderstood that other embodiments may be utilized and structural orlogical changes may be made without departing from the scope of thepresent invention. The following detailed description, therefore, is notto be taken in a limiting sense and the scope of the present inventionis defined by the appended claims.

It is to be understood that the features of the various examplesdescribed herein may be combined with each other, unless specificallynoted otherwise.

FIG. 1 shows a schematic view of a computer system 1, according to oneembodiment of the invention. As shown, the processor or computer system1 has a circuit board 2 on which at least one memory module 3 havingmemory chips is arranged. Each memory module may comprise a circuitboard having a first side and second side, where memory chips arearrangeable on either or both sides. In this example four memory modules3 are attached to the circuit board. The memory modules 3 may beinserted into sockets of the circuit board 2 or they may be arranged ondaughter boards. Further it is possible that the memory chips arearranged directly on the circuit board 2 where the individual memorychips may be assigned virtually to a memory module. This assignment maybe reached for example by the organization of the memory.

The term processor or computer system as it is used herein has variousmeanings. On one hand are the classical computers encompassed forexample server, desktops or laptops on the other hand memorysub-subsystems, plug-in cards or game consoles are encompassed as well.Multimedia devices as for example multimedia computer, video recorder,television sets or beamer are encompassed by the term processor orcomputer system as well. Furthermore network devices as for examplerouter, switches and wireless LAN components are covered by the termprocessor or computer system. The computer system 1 as shownschematically in FIG. 1 can comprise additional not shown components asfor example one or more CPUs, a chipset and one or more slots forexpansion cards.

As shown, a heat transfer system 10 is connected to the computer system1. The heat transfer system 10 may comprise several module heatconductors 11 each of which being in thermal communication with thememory module 3. One end of the module heat conductor 11 may bethermally connected with a removable coupling element 12. The couplingelement 12 may be movably designed so that the memory module 3 togetherwith the module heat conductor 11 can be removed from the circuit board2 (in the case of a socketed memory module).

The coupling elements 12 may connect the module heat conductors 11 witha central heat conductor 13. The central heat conductor 13 may beattached to the circuit board 2 or to a not shown housing for example. Acooling device 14 may be connected to one end of the central heatconductor 13. The cooling device 14 may be arranged as depicted hereoutside of the circuit board 2 or the housing of the computerrespectively. The cooling device 13 can also be arranged on the circuitboard 2 or inside of computer system 1.

The heat transfer system 10 conveys heat from the memory module 3 to thecooling device 14 so that the memory module 3 works in a definedtemperature range. For example, the heat may firstly be carried from thememory module 3 to the module heat conductor 11. For that purpose themodule heat conductor 11 may be attached to a heat spreader of thememory module 3 for example. The thermal coupling may be improved byauxiliary material as for example thermally conductive paste. The heatmay then be carried on through the module heat conductor 11 towards thecoupling element 12 and there conveyed to the central heat conductor 14.The heat may be conveyed in the central heat conductor 13 to the coolingdevice 14 where the heat is brought out of the system. A cooling device14 may comprise cooling fins which may be cooled by for example air orwater. The module heat conductor 11 and the central heat conductor 13may for instance be heat pipes, comprise circulating water or comprise amaterial with good thermal connectivity such as graphite or copper.

FIG. 2 shows schematically a further example of a computer system 21 ina side view, according to one embodiment of the invention. As shown, thecomputer system 21 may comprise several circuit boards 2;Illustratively, two circuit boards are depicted. Every circuit board 2may comprise several memory modules 3 each of which is inserted into asocket 4 of the circuit board 2. The heat transfer system 10 maycomprise, as shown in the example of FIG. 1, module heat conductors 11which are connected to the central heat conductor 13 via couplingelements 12. The central heat conductor 13 may be connected to thecooling device 14. For each circuit board 2 a central heat conductor 13may be provided in the computer system 21. Hence, several central heatconductors 13 may be connected to the cooling device 14. This may be thecase in a server comprising multiple boards or modules.

FIG. 3 depict a part of a further example of a heat transfer system 30.In contrast to the heat transfer system shown in FIGS. 1 and 2 the heattransfer system 30 comprises module heat conductors 31 on both sides ofthe memory modules 3.

FIG. 3A shows a top view of a section of circuit board 2 on whichmultiple memory modules 3 are arranged, according to one embodiment ofthe invention. To each of the memory modules 3 two module heatconductors 31 may be attached, one on each side of the memory modules 3.Depending on conditions of the system as for example available space,heat distribution or airflow it may be possible to mix the memorymodules 3 i.e. use in one system modules equipped with only one moduleheat conductor and memory modules comprising two module heat conductors.

In the following the configuration of the heat transfer system 30 isdescribed in detail. The description starts with the attachment of themodule heat conductor 31 and continues with a thermal coupling of themodule heat conductor 31 with the central heat conductor 33 viaremovable coupling elements 32. The central heat conductor 33 may beconnected to a cooling device which is not depicted.

With regard to FIG. 3C the attachment of the module heat conductor 31 tothe memory modules 3 is now described, according to one embodiment ofthe invention. In this example a heat spreader 5 is arranged at bothsides of the memory module 3. These heat spreaders 5 may be thin metalsheets for example made of aluminum which may cover the entire surfaceof the memory module 3 and are attached using glue or clip elements.Attached to the heat spreader 5 may be a heat guiding plate 34 whichcomprises a recess 35 for accommodation of the module heat conductor 31.The recess 35 may be bent to be adapted to the circumference of themodule heat conductor 31. A thermal interface material as for examplethermally conductive paste may be arranged between the heat spreader 5and the heat guiding plate 34 in order to improve the heat transfer. Theheat guiding plate 34 may be glued onto the heat spreader 5 or may beattached to it with one or more holding clips. The heat spreader 5 andthe heat guiding plate 34 may be a on piece arrangement.

With regard to FIGS. 3A and 3B the coupling element 32 is explained,according to one embodiment of the invention. As shown, the couplingelement 32 or coupling apparatus secures on one hand the memory module 3mechanically and provides on the other hand thermal coupling of themodule heat conductor 31 with the central heat conductor 33. Thecoupling element 32 may be pivot-mounted at the central heat conductor33 so that the coupling element 32 is in thermal and mechanical contactwith the memory module 3 in a closed position and is disconnected fromthe memory module 3 in an open position so that the memory module 3 canbe removed out of the socket 4. In the closed position the couplingelement 32 may contact a contact surface 36 of the module heat conductor31.

With respect to FIGS. 4A and 4B the coupling element 32 is described indetail, according to one embodiment of the invention. To begin with, themechanical fixation of the memory module 3 by means of the couplingelement 32 is described. FIG. 4A shows the coupling element 32 in aclosed position and in an open position in dashed lines. Projections ofthe coupling element 32 may interlock into recesses of the memory module3 so that the memory module 3 is held reliably in the memory socket 4 inthe closed position. During the releasing movement i.e. from closed intothe open state the projections may lift the memory module so thatremoval of the memory module 3 is eased.

Besides the mechanical coupling the coupling element 32 may couple thememory module 3 thermally with the central heat conductor 33. For that,the module heat conductor 31 may comprise a chamfered contact surface 36which is directed towards the coupling element 32 when the memory module3 is inserted. The coupling element 32 may comprise a chamfered contactsurface 37 which contacts the contact surface 36 of the module heatconductor 31 in the closed state. Thermally conductive paste or similarmaterial may be provided on one or both contact surfaces 36, 37respectively to include heat transfer.

As an alternative to contact the frontal contact surface 36 the couplingelement 32 may be shaped in such a way that part of the peripheralsurface of the module heat conductor 31 is contacted. The couplingelement 32 may contact both the peripheral surface of the module heatconductor 31 and the frontal contact surface 36 when the frontal contactsurface 36 may be chamfered or not.

The material of the coupling element is selected such that good heattransfer from the contact surface 36 of the module heat conductor 31 tothe central heat conductor 33 takes place. For example aluminum, copperor graphite may be chosen. The module heat conductor 31 and/or thecentral heat conductor 33 may for example be designed as heat pipes.

This embodiment shows the coupling device or in other words theremovable coupling element 32 made out of one piece which enables boththe mechanical and the thermal coupling. The coupling element may bedesigned in two pieces wherein one part does the mechanical coupling andthe second part does the thermal coupling. Both parts may be connectedso that for example upon actuation of the mechanical part the thermalcoupling is established as well.

FIG. 5A shows a heat transfer system 40, according to another embodimentof the invention. The heat transfer system 40 cools memory modules 3which are inserted into memory sockets 4 which in turn are arranged on acircuit board 2. In this embodiment the inserted memory modules 3 arenot arranged perpendicular with regard to the circuit board 2 but undera smaller angle. Server systems use this arrangement often. The heattransfer system 40 may comprise module heat conductors 41 attached tothe memory modules 3, a central heat conductor 43 and removable couplingelements 42 which connect the module heat conductor 41 with the centralheat conductor 43. The central heat conductor 43 may be connected to acooling device (not shown).

FIG. 5C shows the attachment of the module heat conductor 41 to thememory module 3, according to one embodiment of the invention. A heatguiding plate 44 transfers the heat from the sides of the memory module3 towards the module heat conductor 41.

As it is seen in FIG. 5B, the module heat conductor 41 extends over theheat guiding plate 44 in longitudinal direction of the memory module sothat the extending end of the module heat conductor 41 can be connectedwith a coupling element 42 in a removable manner, according to oneembodiment of the invention.

With reference to FIG. 5A, the coupling element 42 may comprise a firstpart 42 a which may be permanently connected to the central heatconductor 43 and a removable second part 42 b. The second part 42 b canbe fastened to the first part 42 a by for example a clip, bayonetcoupling, a bolt connection or as shown here with screws 46. The firstpart 42 a may have a recess or a bore hole so that it can be put on thecentral heat conductor 43. Thermally conductive paste may be provided inthe bore hole to increase heat transfer between the coupling element 42and the central heat conductor 43. The first part 42 a may have a recessin form of a half cylinder in its contact surface to the second part 42b. The longitudinal axis of the recess may be orientated approximatelyat a right angle with regard to the longitudinal axis of the bore holefor the central heat conductor. The recess may be provided in such aform that the module heat conductor 41 has contact as extensive aspossible to the first part 42 a. A corresponding recess is in the secondpart 42 b provided so that the whole circumference of the module heatconductor 41 is enclosed by the two parts of the coupling element 42 inan assembled state of the coupling element 42.

In the following a change of a memory module 3 is described. To removethe inserted memory module 3 the screws 46 of the corresponding couplingelement 42 may be loosened thereupon the second part 42 b is removedwhereupon the memory module 3 can be removed from the socket 4. The newmemory module 3 may be inserted into the socket 4, in doing so themodule heat conductor 41 is moved into the recess of the first part 42a. Once the memory module 3 is inserted tightly into the socket 4, thesecond part 42 b is attached to the first part 42 a with use of thescrews 46 so that the memory module 3 is now firmly connected to thecentral heat conductor 43.

In the embodiments described above reference is made to memory modules.The invention is however not restricted to memory modules. In fact theinvention can be used with other pluggable modules or cards as forexample processor or graphic cards, cards for acceleration of physicalcomputations or pluggable power modules. In a broader sense theinvention can be used with all types of pluggable cards which benefitfrom heat dissipation.

1. A memory module, comprising: a circuit board with a first and asecond side; memory chips, which are arranged at least on the firstside; and a longitudinally extending module heat pipe, which is arrangedon the first side, wherein the module heat pipe forms a heat transfersystem contact surface configured to contact a heat transfer system. 2.The memory module of claim 1, wherein a second module heat pipe isarranged at the second side.
 3. The memory module of claim 1, wherein acontact surface is arranged at one end of the module heat pipe and ischamfered.
 4. The memory module of claim 1, wherein the module heat pipeis arranged in a recess of a heat guiding plate which covers one side ofthe circuit board at least partially.
 5. A circuit board, comprising: atleast one memory socket; a coupling device configured to fasten a memorymodule in the memory socket; and a heat transfer system comprising acentral heat conductor and the coupling device, wherein at least part ofthe coupling device is thermally conductive and in thermal communicationwith the central heat conductor, and wherein the coupling devicecomprises a contact surface configured for thermal communication withthe memory module.
 6. The circuit board of claim 5, wherein the contactsurface is chamfered.
 7. The circuit board of claim 5, wherein thecoupling device comprises two contact surfaces.
 8. The circuit board ofclaim 5, wherein the coupling device is pivot-mounted on the centralheat conductor.
 9. The circuit board of claim 5, wherein the couplingdevice has a clip comprising metal or graphite.
 10. The circuit board ofclaim 5, wherein the coupling device comprises a clip configured formechanical coupling and a heat transfer device configured for thermalcoupling of the memory module.
 11. The circuit board of claim 5,comprising a cooling device, which is connected to the central heatconductor.
 12. The circuit board of claim 5, comprising several memorysockets and several coupling devices, wherein the coupling devices arein thermal communication with the central heat conductor.
 13. Thecircuit board of claim 5, wherein at least one of the module heatconductor and the central heat conductor is a heat pipe.
 14. A heattransfer system for a memory system, comprising: at least one moduleheat conductor which is attachable to a memory module; a central heatconductor; removable coupling elements, which couple the module heatconductor and the central heat conductor thermally; and a coolingdevice, which is coupled to the central heat conductor.
 15. The heattransfer system of claim 14, wherein at least one of the module heatconductor and the central heat conductor is a heat pipe.
 16. The heattransfer system of claim 14, wherein the module heat conductor comprisesa heat guiding plate and wherein the central heat conductor comprises aheat pipe.
 17. The heat transfer system of claim 14, wherein thecoupling element couples the memory module mechanically.
 18. The heattransfer system of claim 14, wherein the central heat conductor isattachable to a circuit board on which a socket for the memory module isarranged.
 19. The heat transfer system of claim 14, wherein the couplingelement is non-removably connected with the central heat conductor. 20.The heat transfer system of claim 14, wherein the coupling element ispivot-mounted on the central heat conductor.
 21. A computer system,comprising: at least one circuit board, comprising: at least one memorysocket; a coupling device configured to fasten a memory module in thememory socket; and a heat transfer system comprising a central heatconductor and the coupling device, wherein at least part of the couplingdevice is thermally conductive and in thermal communication with thecentral heat conductor, and wherein the coupling device comprises acontact surface configured for thermal communication with the memorymodule; and at least one memory module fastened to the at least onememory socket, comprising: a circuit board with a first and a secondside; memory chips, which are arranged at least on the first side; and alongitudinally extending module heat pipe, which is arranged on thefirst side, wherein the module heat pipe forms a heat transfer systemcontact surface configured to contact a heat transfer system;
 22. Acomputer system, comprising: a circuit board comprising at least onememory socket for a memory module; at least one memory module; and aheat transfer system, comprising: at least one module heat conductorwhich is attachable to the at least one memory module; a central heatconductor; removable coupling elements, which thermally couple themodule heat conductor and the central heat conductor; and a coolingdevice, which is coupled to the central heat conductor.